Ruiping Deng

Two-Step Relaxation in a Linear Tetranuclear Dysprosium(III) Aggregate Showing Single-Molecule Magnet Behavior

A well-defined two-step relaxation, described by the sum of two modified Debye functions, is observed in a new alkoxido-bridged linear tetranuclear Dy(III) aggregate showing single-molecule magnet behavior with a remarkably large energy barrier. This compound represents a model molecular aggregate with a clear two-step relaxation evidenced by frequency-dependent susceptibility, which therefore may stimulate further investigations regarding the relaxation dynamics of lanthanide-based systems.

Engineering white light-emitting Eu-doped ZnO urchins by biopolymer-assisted hydrothermal method

With the presence of biopolymer-sodium alginate as additive, Eu-doped ZnO (zinc oxide) urchins consisting of nanorods were synthesized through a hydrothermal route. X-ray diffraction pattern makes evident the absence of phase other than wurtzite ZnO. Upon excited by 325nm xenon laser, such nanostructured Eu-doped ZnO urchins emit white light, which originates from the luminescence of ZnO and the intra-4f transitions of Eu3+ ions. Besides acting as stabilizing agent, sodium alginate may also sensitize the Eu3+ ions in the nanostructures and facilitate the energy transfer from the host to Eu3+ ions.

Novel Multifunctional Nanocomposites: Magnetic Mesoporous Silica Nanospheres Covalently Bonded with Near-Infrared Luminescent Lanthanide Complexes

In this paper, we report the fabrication and characterization of magnetic mesoporous silica nanospheres covalently bonded with near-infrared (NIR) luminescent lanthanide complexes [denoted as Ln(DBM)(3)phen-MMS (Ln = Nd, Yb)]. Ln(DBM)(3)phen-MMS (Ln = Nd, Yb) nanospheres with an average size of 80-130 nm were synthesized via incorporation of the chelate ligand 5-[N,N-bis-3-(triethoxysilyl)propyl]ureyl-1,10-phenanthroline (phen-Si) into the framework of magnetic mesoporous silica (denoted as phen-MMS), followed by introduction of the Ln(DBM)(3)(H(2)O)(2) (Ln = Nd, Yb) complexes into the nanocomposites via a ligand exchange reaction. The morphological, structural, textural, magnetic, and NIR luminescent properties were well-characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N(2) adsorption-desorption, a superconducting quantum interference device (SQUID), and photoluminescence spectra. These nanocomposites, which possess high surface area, high pore volume, and well-defined pore size, exhibit two-dimensional hexagonal (P6mm) mesostructures. After ligand-mediated excitation, Ln(DBM)(3)phen-MMS (Ln = Nd, Yb) nanocomposites exhibit the characteristic NIR emission of Nd(3+) and Yb(3+), respectively. Magnetic measurements reveal that these mulfunctional nanocomposites possess superparamagnetic properties at 300 K. The high magnetization values make the nanocomposites respond to the external magnetic field quickly. Additionally, the results indicate that Nd(DBM)(3)phen-MMS nanocomposites may have potential applications for laser systems or the optical amplifiers operating at 1.3 microm and Yb(DBM)(3)phen-MMS nanocomposites have several advantages for potential applications in drug delivery or optical imaging.

Incorporation of luminescent lanthanide complex inside the channels of organically modified mesoporous silica via template-ion exchange method

Luminescent lanthanide complex, Eu(phen)2Cl3·2H2O (Euphen, phen = 1,10-phenanthroline) has been incorporated inside the channels of mesoporous silica MCM-41 with its external surface modified by phenyltriethoxysilane (Ph-Si(OEt)3) via a simple template-ion exchange method. The passivation of active groups such as silanols in the external surface ensures that the ion exchange reaction occurs between the surfactant cations and the lanthanide complex ions inside the channels of the modified MCM-41. The passivation result is confirmed by 29Si MAS NMR spectroscopy. FT-IR demonstrates that the cationic surfactants are completely removed. XRD and N2 adsorption–desorption measurements are employed to characterize the mesostructure of Euphen-Ph-MCM-41. Luminescence and stability studies on the materials of Euphen and Euphen-Ph-MCM-41 show that the resultant hybrid material Euphen-Ph-MCM-41 exhibits the characteristic emission of Eu3+ ions under UV irradiation with higher 5D0 luminescence quantum efficiency, longer lifetime and better thermal stability than the corresponding pure complex Euphen. Moreover, the characterization results show that the local symmetry and the first coordination shell of Eu3+ ions are changed after the complex ions become incorporated into the MCM-41 channels and that a more symmetric environment is occupied by the Eu3+ ions in Euphen-Ph-MCM-41 than in Euphen. There is also a more efficient ligand-to-Eu(III) intramolecular energy transfer process in Euphen-Ph-MCM-41.

Porous Co3O4 microcubes: hydrothermal synthesis, catalytic and magnetic properties

Well-defined porous Co3O4 microcubes have been synthesized by a simple one-pot solvothermal method combined with subsequent calcination. The formation mechanism of the cube-like precursor was proposed based on the anisotropic intrinsic structure of CoCO3. Importantly, after thermal treatment, the cube-like morphology could be completely preserved. Moreover, the thermal decomposition of the corresponding precursor led to the formation of porous structure. The effects of calcination temperature on the catalytic properties of Co3O4 samples were investigated and the results demonstrated that 600 °C was superior among three samples with the highest catalytic properties. Additionally, as an antiferromagnetic material, the sample showed a certain degree of ferromagnetism under the external magnetic field.

Synthesis, structure and luminescent properties of a new praseodymium(III) complex with beta-diketone

A new tetrakis praseodymium(tu) complex Pr(TFNB)(3)Phen has been synthesized, in which TFNB is 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione and Phen is 1,10-phenanthroline. Its crystal structure and luminescent spectra were successfully determined and investigated. The typical antenna effect existing in the luminescence of Pr(TFNB)(3)Phen was revealed by the study of the UV-Vis absorption spectra of ligands and the excitation spectrum of Pr(TFNB)(3)Phen.

Semiconducting Polymer Dots Doped with Europium Complexes Showing Ultranarrow Emission and Long Luminescence Lifetime for Time‐Gated Cellular Imaging

Bright dots: Semiconducting polymer dots (Pdots) doped with europium complexes possess line-like fluorescence emission, high quantum yield, and long fluorescence lifetime. The Pdots successfully labeled receptors on cells. The long fluorescence lifetime of the Pdots was used to distinguish them from other red fluorescence emitting nanoparticles, and improve the signal-to-noise ratio for time-gated cellular imaging. PVK=poly(9-vinylcarbazole).

Three p-tert-Butylthiacalix[4]arene-Supported Cobalt Compounds Obtained in One Pot Involving In Situ Formation of N6H2 Ligand

Three p-tert-butylthiacalix[4]arene (H(4)TC4A)-supported Co(II) compounds, [Co(4)(TC4A)(N(3))(4)(N(6)H(2))(CH(3)OH)](CH(3)OH)(2) (1), [Co(8)(TC4A)(2)(N(3))(2)(N(6)H(2))(2)(CH(3)COO)(4)(CH(3)OH)(4)](OH)(2)(CH(3)OH)(4) (2), and [Co(10)(TC4A)(4)(N(3))(4)](CH(3)OH)(4) (3), have been solvothermally obtained in one pot and structurally characterized by single-crystal X-ray diffraction analyses, powder XRD, and IR spectroscopy. This work presents the first one-dimensional (1) cobalt cluster for the calixarene complexes and another two octanuclear (2) or decanuclear (3) cobalt clusters. In the structures of compounds 1 and 2, a novel N(6)H(2) ligand formed by the in situ (2 + 3) cycloaddition of two azides was observed. Density functional theory (DFT) calculations give the heat of formation (2N(3)(-) + 2H(+) --> N(6)H(2)) and decomposition energy (N(6)H(2) --> 3N(2) + H(2)) of 677.47 and 124.85 kcal/mol, respectively. Furthermore, an intergradation was determined at the B3LYP/6-311++g(d,p) level for the formation of the N(6)H(2) ligand. In addition, one TC4A ligand of a sandwich unit adopts a cone conformation, while the other adopts a pinched cone conformation in 3. The magnetic properties of these three compounds were influenced mainly by the orbital contributions of the distorted octahedral Co(II) ions.

Raisin-like rare earth doped gadolinium fluoride nanocrystals: microwave synthesis and magnetic and upconversion luminescent properties

Bifunctional lanthanide doped 3D raisin-like GdF3 nanocrystals were synthesized by a microwave method. The influences of synthesis parameters on the final morphology were investigated and the morphology can be tuned to snow-like microcrystals and nanocrystals. The as-prepared samples possess properties of multicolor upconversion (UC) photoluminescence (PL) and paramagnetism. To understand the magnetic mechanism, temperature dependence of zero-field cooling (ZFC) and field cooling (FC) magnetization of the raisin-like GdF3 nanocrystals were studied.

Precursor induced synthesis of hierarchical nanostructured ZnO

As-synthesized ZnO nanostructures with a bladed bundle-like architecture have been fabricated from a flower-like precursor ZnO.0.33ZnBr(2).1.74H(2)O via a mechanism of dissolution-recrystallization. Experimental conditions, such as initial reactants and reaction time, are examined. The results show that no bladed bundle-like ZnO hierarchical nanostructures can be obtained by using the same molar amount of other zinc salts, such as ZnBr(2), instead of the flower-like ZnO.0.33ZnBr(2).1.74H(2)O precursor, and keeping other conditions unchanged. The products were characterized by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The ZnO nanostructures are mainly composed of nanowires with a diameter around 40-50 nm and length up to 1.5-2.5 microm. Meanwhile, ZnO nanoflakes with a thickness of about 4-5 nm attached to the surface of ZnO nanowires with a preferred radially aligned orientation. Furthermore, the photoluminescence (PL) measurements exhibited the unique white-light-emitting characteristic of hierarchical ZnO nanostructures. The emission spectra cover the whole visible region from 380 to 700 nm.